Electric-lighting system.



Patented Feb. 6, I900.

A. C. M. PRUCKER.

ELECTRIC LIGHTING SYSTEM.

(Application filed Sept. 2, 1899.)

(No llodel.)

d MI

III I WIIIIIIIIIII? 114: "ohms PD!!! 00., Pam-ammo wuumamu. 04 c.

UNITED STATES PATENT OFFICE;

AMAND CARL MARIA PRI ICKER, OF HANOVER, GERMANY, ASSIGNOR TO THE SIEMENS& I-IALSKE ELECTRIC COMPANY OF AMERICA, OF CHICAGO,

ILLINOIS.

ELECTRI C-LIG HTING SYSTEM SPECIFICATION forming part of Letters PatentNo. 642,627, dated February 6, 1900. Application filed September 2,1899.Serial No. 729,339. (No model.)

To all whom it may concern:

Be it known that I, AMAND CARL MARIA PRUCKER, a subject of the Emperorof Austria-Hungary,residing at Hanover, in the German Empire, haveinvented a certain new and useful Improvement in Electric-LightingSystems, (Case No. 239,) of which the following is a full, clear,concise, and exact description, reference being had to the accompanyingdrawing, forming a part of this specification.

My invention relates to systems of electric lighting, and has for itsobject the provision of means and a system wherein contact parts ofelectric lamps maybe exposed without danger of having shocks imparted.

As is Well known, incandescent electric lamps now commonly employed havetheir contact portions soinclosed that they may not ordinarily be touched, to prevent shocks. The exercise of this precaution in themanufacture .of incandescent lam ps is costly, as the plug portions ofthe lamps have to be surrounded by insulating material and the wholeinclosed by a suitable casing.

In accordance with my invention I employ the IIopkinson three-wiresystem of directcurrent distribution, constituting a seriesmultiplesystem, the incandescent lamps being connected across the mains and witha compensating conductor. The compensating conductor is grounded at thegenerating-station. The lamps in accordance with my invention each havethat terminal which is connected with one of the main conductorsinclosed so as normally to be inaccessible, the other terminal of thelamp constituting the casing for the plug portion thereof and which isconnected either directly with the ground at the district ofdistribution or with the compensating conductor. I am thus enabled toproduce a lamp when it is employed in a threewire system constructed asspecified, wherein an exposed metallic contact portion may be employedwithout danger. This metallic contact portion may be in the form of ametallic jacket provided with screw-threads. adapted for directconnection with a metallic pipe, for example, having connection with thegrounded or compensating conductor and through which a wire may be ledconnected with the which are connected the mains b b, supplying 1 twogroups of translating devices 0 0, these translating devices beingseparated into groups by a neutral or compensating conductor cl,preferably extending from the district of distribution to the point ofdivision between the generators. The compensating condoctor is groundedat the generators.

I have shown an incandescent lamp 6 connected between the compensatingand a main conductor. The external screw-threaded metallic coveringf ofthe lamp is in direct connection with a contact part g of the lamp. Thiscovering preferably has threaded engagement with the metallic nipple h,which in turn preferably has threaded engagement with another metallicnipple 2'. The latter nipple may in any suitable manner be connecteddirectly with the earth, preferably by having threaded engagement with ametallic interior conduit 70, connected either to earth or directly withthe grounded compensating conductor. Inside of the hollow cylindricalportion formed by the covering of the lamp I preferably place a hollowinsulating-block-m, within which is disposed a ring of porcelain n.Within this ring of porcelain I place a metallic contact-ring 0, towhich is connected the conducting-wire 19, having connection at itsother end with a main conductor of the system. I interpose a switchbetween the latter condu ctor, extending from the main and the filamentof the lamp, rather than in the conductor unit- 'ing the other terminalof the filament with the compensating conductor, so that when the lampis out of service the exposed metallic parts thereof will not be chargedwith current from the main wire to avoid shocks which might otherwiseoccur if the switch were included in the connection with thecompensating conductor.

It will be seen that I dispense with two wires threading a conduit forconnection with the lamp, a single wire and a metallic conduit inclosingthe same being used to carry the current without danger.

I do not wish to be limited to the precise form of lamp mechanism shown;but,

Having thus described my invention, I claim as new and desire to secureby Letters Patent 1. In a system of electrical distribution, thecombination with a source of current connected with main andcompensating conductors, the compensating conductor being grounded, of atranslating device, a conductor leading from a main and connected withone terminal of the translating device, a grounded metallic conduitthrough which said conductor is led,

having connection with the other terminal of the translating device, anda switch in the last aforesaid conductor, substantially as described.

2. In a system of electrical distribution, the combination with a sourceof current connected with main and compensating conductors,

combination with a source of current connected with main andcompensating conductors, the compensating conductor being grounded, ofan incandescent electric lamp having one terminal connected, or adaptedfor connection, with a main conductor, a switch included between thesaid main conductor and the said terminal, the other terminal beinggrounded, substantially as described.

4. In a system of electrical distribution, the combination with a sourceof current connected with main and compensating conductors, thecompensating conductor being grounded, of a metallic conduit,anincandescent electric lamp, one of whose terminals is adapted forconnection with said conduit, the said conduit being grounded, aconductor inclosed by said conduit uniting the otherterminal of the lampwith the main conductors of the system, and a switch included in theconductor uniting the latter terminal with a main conductor of thesystem, substantially as described.

5. In a system of electrical distribution, the combination with a sourceof current connected with main and compensating conductors, thecompensating conductor being grounded, of a translating device havingone terminal connected, or adapted for connection, with a mainconductor, a switch included between the said main conductor and thesaid terminal, the other terminal being grounded, substantially asdescribed.

In witness whereof I here unto subscribe my name this 4th day of August,A. D. 1899.

AMANI) CARL MARIA PRUOKER.

Witnesses:

LEoNoRE' KASGH, KIRKE LATHRor.

